A Study of Compound Action Potentials in Current-Coupled Tracts: the General Case

In this paper, the authors investigate compound action potentials formed when the underlying tract's axons have current-mediated coupling amongst themselves, and no field-mediated coupling. The key finding of the paper is that, for the case of biophysically inhomogeneous axon tracts, the compound action potential is governed by a Hodgkin-Huxley like equation itself in certain cases. The paper extends an earlier result for the identical axon case.

Study on scour around vertical large-size cylinder base due to combined action of wave and current

Based on the mechanism of local scour around vertical large-sized cylinder due to combined action of wave and current,the sour morphology,scour process and the maximum scour depth around the cylinders are studied experimentally.The influence of various ocean environmental parameters on local scour around the cylinder is considered in physical model test.The experimental results indicate that the principal effect factors on the scour in fine-sand seabed are wave height,wavelength,current velocity,ratio of diameter to wavelength and ratio of depth to wavelength when the ratio of cylinder diameter to wavelength is from 0.2 to 0.8.In this paper,dimensional analysis theory is utilized to establish a theoretical equation for forecasting maximum scour depth around large-sized round cylinder base due to the combined action of wave and current.The results computed with the theoretical equation are compared with the experimental results,and found to be in good consistency.The results in this studies can be used to estimate the maximum sour depth around analogous structures.

A Higher Order BEM for Wave-Current Action on Structures—Direct Computation of Free-Term Coefficient and CPV Integrals

A higher order boundary dement method （HOBEM） is implemented for wave-current action on structures. The freeterm coefficient and Cauchy principal value （ GPV） integrals are computed by direct methods. Numerical experiments are carried out to validate the computation of free-term coefficient and GPV integrals. The results show that the computation precision of free-term coefficient is very high for various bodies, even with edges and corners, and the convergence speed is fast for CPV integrals for different meshes. The comparison of the second order mean drift force due to wave-current action on a uniform cylinder is made with an analytic solution. It is found that good agreement exists between the present calculation and the analytic solutions. Finally, the numerical code is applied for computing wave-current action on Snorrc TLP.

Damage Evolution of Concrete under the Actions of Stray Current and Sulphate

Based on the mechanism of stray current generation in underground structures,the concrete durability test device for stray current and sulphate in typical soil environment was designed to study the damage of concrete under the action of stray current and sulphate.The deterioration law of concrete under the action of stray current and sulphate was studied by microscopic techniques such as scanning electron microscopy (SEM) and X-ray diffraction (XRD).The microstructure of corroded concrete was observed to determine the phase composition of erosion products.The damage performances such as quality,strength,and dynamic elastic mode of corroded concrete were performed.The experimental results show that,under the action of stray current,the products of sulfate-eroded concrete are mainly gypsum,ettringite,and thaumasite;the stray current accelerates the hydration process of cement and the erosion of concrete by sulfate;when the concrete pores are filled with the erosion product,there is an increase of approximately 10% in the concrete compressive strength and dynamic elastic modulus;and the concrete compressive strength is more sensitive to the stray current electrification period than the current intensity.

Numerical Simulation for Refraction-Diffraction of Waves in Water of Slowly Varying Current and Topography

A new numerical finite difference iteration method for refraction-diffraction of waves ia water of slowly varying current and topography is developed in this paper. And corresponding theoretical model including the dissipation term is briefly described, together with some analysis and comparison of computational results of the model with measurements in a hydraulic scale model (Berkhoff et al., 1982). An example of practical use of the method is given, showing that the present model is useful to engineering practice.

CHARACTERISTICS OF ACTIONPOTENTIAL AND THEIR UNDERLYING OUTWARD CURRENTS IN MAMMALIAN TASTE RECEPTOR CELLS

Many rat taste receptor cells conduct action potentials(APs).APs had a mean threshold of -35 mV(n=95 cells)and a spike height of 52mV above threshold in current clamp(hold= -80mV).Aps could be classified into two significantly different (P<0.001) groups-fast,with short half-time durations and large outward currents (mean1.3 ms and 2.7nA),and slow,with long duration and small outward currents(mean9.2ms and 0. 29nA).AP upstrokes were conducted by TTX-sensitive sodium currents whereas the downstroke by TEA-blockable outward currents. Voltage dependent analysis of outward current separated transient and sustained components.The transient component was specifically blocked by 4-AP(1mmol/L).A calcium-dependent outward component was also revealed modulating voltage and external calcium concentration.The fast recovery phase of the AP appears related the sustained outward current whereas the after hyperpolarization(AHP) was blocked by 4AP suggesting a significant contribution of the transient component.Forskolin (FSK),which elevates cAMP,reversibly blocked the majority of the sustained current without influencing the transient. FSK greatly exaggerated the AHP without changing the spike height or duration. These data suggest that several components of the outward current contribute specifically to the gustatory AP and that the AP may be modulated by cyclic nucleotides.

Generalized Mean-Flow Theory of Wave-Current-BottomInteractions

The interaction between waves, currents and bottoms in estuarine and coastal regions is ubiquitious, in particular the dynamic mechanism of waves on large-scale slowly varying currents. The wave action concept may be extended and applicated to the study of the mechanism. Considering the effects of moving bottoms and starting from the Navier-Stokes equation of motion of a vinous fluid including the Coriolis force, a generalized mean-flow medel theory for the nearshore region, that is, a set of mean-flow equations and their generalized wave action equation involving the three new kinds of actions termed respectively as the current wave action, the bottom wave action and the dissipative wave action which can be applied to arbitrary depth over moving bottoms and ambient currents with a typical vertical structure, is developed by vertical integration and time-averaglng over a wave peried, thus extending the classical concept, wave action, from the ideal averaged flow conservative system to the real averaged flow dissipative dynamical system, and having a large range of application.

Research on Characteristics of Density Current Under the Action of Waves

In this paper, the characteristics of density current under the action of waves are described with the help of flume experiment and theoretical analysis. The study shows that turbid water under the action of the waves can present three types of motion, i. e. significant stratification, fragile stratification and strong mixing. The motion gf turbid;,ater presents significant stratification when (H/D)/root Delta rho/rho less than or equal to 4.5, generally this state is known as density current. The formulas of motion velocity, thickness, and discharge of density current moving on horizontal bottom are derived by use of basic equations such as momemtum equation, equation of energy conservation and continuity equation of fluid. The time-average velocity and the thickness of density current under the action of waves have a relationship with such parameters as relative density (Delta rho/rho), wave height (H), and water depth (D). When these parameters are determined, the time-average thickness and motion velocity of density current are also determined. The relative thickness of density current (D-t/D) decreases with the increase of Delta rho/rho and increases with the increase of H/D. On the other hand, the motion velocity of density current increases with the increase of Delta rho/rho and decreases with the increase of the relative thickness (D-t/D) of density current. It is shown that the calculated results are in agreement with those of the flume experiment.

Refraction-Diffraction Model for Irregular Wave and Directional Spectrum Considering Current

A mild-slope equation for combined refraction and diffraction of random waves in the independent time current is derived using Kirby equation(1984). In the derivation, the frequency of random waves is represented based on the time series concept, by a typical frequency and its deviation part. Numerical results, compared with those of laboratory experiments, demonstrate that new set of irregular mild slope equation with current is of good adaptability.

环状RNA mmu_circ_0005019影响小鼠心肌细胞钙激活钾通道电流及动作电位

目的 探索环状RNA mmu_circ_0005019调控小电导钙激活钾(small-conductance calcium-activated potassium, SK)通道蛋白亚基SK3编码基因Kcnn3的表达,以及对小电导钙激活钾通道电流(IK,Ca)和动作电位时程(action potential duration, APD)的影响。方法 在小鼠HL-1细胞中分别构建mmu_circ_0005019过表达和干扰模型,分为过表达组(n=3)、空质粒组(n=3)、干扰1组(n=3)、干扰2组(n=3)、对照组(n=3),通过RT-qPCR、Western blot分析mmu_circ_0005019调节Kcnn3表达的分子机制,应用膜片钳技术电流钳模式记录全细胞的IK,Ca,并用电压钳模式记录APD。结果 成功构建了环状RNA mmu_circ_0005019过表达和干扰的HL-1细胞模型。过表达组的Kcnn3基因表达与空质粒组相比明显上调(P<0.05);干扰1组和干扰2组的Kcnn3基因表达与对照组相比均明显下调(P<0.05)。电生理发现过表达mmu_circ_0005019增加了HL-1细胞IK,Ca电流密度,APD显著缩短;相反,干扰mmu_circ_0005019减少了IK,Ca电流密度,APD显著延长。结论 mmu_circ_0005019可以上调小鼠HL-1细胞Kcnn3的表达水平,从而改变IK,Ca和APD,提示环状RNA mmu_circ_0005019可能在房颤发生中起到促进作用。

新型旋转减冲装置对桩基局部冲刷防护试验研究

为减轻海上风电单桩基础周围局部冲刷对其结构安全的影响,本文提出了一种新型旋转减冲装置。在波流水槽中开展物理模型试验,改变波流条件、装置安装高度、安装距离,记录桩周冲刷发展历时,运用激光地形仪扫描冲刷坑形态,分析各工况下冲刷坑形态差异,验证装置不同安装距离、安装高度下的冲刷防护效果,提出了不同安装位置下的防护效率公式。结果表明:新型旋转减冲装置具有较好的冲刷防护效果,本试验工况下,桩周最大冲刷深度可减小44%左右。装置安装距离对冲刷防护效果影响较小,波流作用下的冲刷防护效果受装置安装高度影响显著,冲刷防护效果随装置安装高度的增加而减弱。

基于环流相似度的变压器零模涌流识别与零序保护方法

随着我国电力系统规模的扩大和输电容量的增加,Yd连接的高阻抗变压器得到了广泛应用。传统的变压器零序差动保护采用二次谐波比进行涌流制动,但该方法在空投于内部故障时会出现拒动情况。提出了一种基于环流相似度的变压器零模涌流识别与零序保护方法,该方法计算原方零模涌流和副方环流的波形相似度,再根据变压器三相的饱和系数识别内部故障,综合实现变压器准确的涌流闭锁。仿真和实验结果表明,所提保护方法在变压器和应涌流及空投于内部故障情况下均能正确动作。

口面部疼痛模型小鼠前扣带回皮质神经元电生理特性研究

目的观察完全弗氏佐剂(complete Freund’s adjuvant,CFA)诱导的口面部疼痛模型小鼠大脑前扣带回皮质(an⁃terior cingulate cortex,ACC)神经元电生理特性。方法将18只小鼠随机分为Sham组和CFA组,CFA组小鼠右侧面部胡须垫下注射CFA,构建口面部疼痛模型。Sham组小鼠注射生理盐水。用Von⁃Frey细丝检测口面部机械性疼痛阈值,采用膜片钳方法观察Sham组和CFA组小鼠ACC神经元兴奋性突触后电流(excitatory postsynaptic current,EPSC)和动作电位(action potential,AP)的发放情况。结果与Sham组相比,CFA组小鼠面部胡须垫下注射CFA后诱发机械性疼痛阈值较低(P<0.05)。CFA组小鼠ACC脑区神经元的EPSC的频率和幅值均高于Sham组(P<0.05)。当刺激电流在100、125、150、175、200 pA时,CFA组小鼠ACC脑区神经元的AP发放次数高于Sham组(P<0.05)。结论ACC脑区神经元活性在口面部疼痛的发生与发展中呈现增加的趋势,可能与口面部疼痛的形成密切相关。

基于网衣壁面展开法的网目群化拟合关系分析

针对网衣构建过程复杂且在网目群化过程中网线重力与浮力的相对误差会降低水动力性能评估的准确性,建立一种网衣壁面展开建模算法,该方法根据网衣三维壁面展开为二维壁面的建模原理,调整网目群化度,以控制建模精细程度。基于Orca Flex使用此算法对比相关研究结果,验证数值模拟与算法的有效性。据此在纯流载荷下对不同网深的平面网衣、不同网径的圆柱形网衣,于不同网目群化度下进行水动力数值模拟,得出线缆拖曳力的相关线性拟合关系。分析得知网深越深、网径越大,即群化前网目数量越大,拟合函数敏感度越高。使用拟合函数可得到群化前网衣的水动力拖曳数值,大幅缩减网目群化度增大所带来的相对误差。

经颅交流电刺激治疗神经精神疾病认知功能损害研究进展

认知功能障碍是脑高级功能的损伤,由神经精神疾病引起的认知功能损害对患者的生活质量和疾病转归造成严重影响。经颅交流电刺激(transcranial alternating current stimulation,tACS)通过调节特定频率的神经振荡、影响5-羟色胺和多巴胺等神经递质的释放、增强脑网络局部与远端的同步,达到改善认知功能的效果。特定频率的tACS可以改善阿尔茨海默病(Alzheimer disease,AD)、精神分裂症、抑郁障碍引起的认知功能损害,其中以gamma和theta频率tACS对认知功能的影响最为显著。tACS安全性高,操作难度小,对改善神经精神疾病患者的认知功能具有巨大潜力。

Numerical Simulation of Local Scour Around A Large Circular Cylinder Under Wave Action

A horizontal two-dimensional numerical model is developed for estimation of sediment transport and sea bed change around it large circular cylinder tinder wave action, The wave model is based on an elliptic mild slope equation. The wave-induced current by the gradient of radiation stress is considered and a depth integrated shallow water equation is applied to the calculation of the current. The mass transport velocity and the bed shear stress due to streaming are considered, which are important factors affecting the sediment transport around a structure due to waves, especially in reflective areas. Wave-current interaction is taken into account in the model for computing the bed shear stress. The model is implemented by it finite element method, The results of this model are compared with those from other methods and agree well with experimental data.

Hydrodynamic Characteristics of Submarine Composite Pipeline in a Wave-Current Coexisting Field

-A composite pipeline is defined as a pipeline system composed of one big pipe and one or several small pipes. Based on the theory of wave- current interaction and physical model test, the hydrodynamic characteristics of the submarine composite pipeline in wave-current coexisting field (both regular and irregular waves) are investigated. The so-called 'modified diameter method' is used for analyzing the in-fine hydrodynamic coefficients of the composite pipeline, which are well related to KC number. The comparison of test data for regular and irregular waves shows that in the region of 90 > KC> 20, the results in these two cases can be unified. The effect of water depth is analyzed in details. The relationships between CD, CM and KC , which are based on the results of present research, may be used as a reference in engineering design.

波流作用下高桩码头动力响应试验研究

针对外海工程地质环境,以高桩码头为研究对象,设计波流作用下水槽试验方案,开展波流作用下高桩码头动力响应的试验研究,还原了高桩码头真实的使用环境,探讨高桩码头桩身内部响应差异,分析自由场与桩周土孔压和加速度的响应关系。结果表明:1)高桩码头各桩响应差异明显,顺波流方向桩身所受动水压力逐渐减小,桩身弯矩前排桩大于后排桩,中间桩大于两侧桩;2)面板位移和加速度呈周期性变化,扭转随波流作用逐渐减小;3)土层加速度和孔压随波流传播和埋深增加逐渐减小,群桩的存在会增大土层加速度、减小孔压;4)高桩码头设计时,应适当提高中间桩的强度,重视对表层海床土的加固。研究成果可为高桩码头的设计和维护提供一定的参考与借鉴。